The present invention relates generally to conveyor and stacking systems for a magazine of articles. More specifically, this invention relates to a continuous conveyor having a plurality of pivotable guide bars, a stacking and alignment area at its input end, and at a vertical lid feeder at its output end from which the lids are transported for application onto containers. The present invention also concerns a method for stacking, conveying and lifting a plurality of lid stacks for application onto containers.
Devices for both stacking, unstacking, and conveying stacks of articles, such as flat or sheet-like products, have been developed for the quick and easy processing or packaging of these articles for various purposes. See for example, U.S. Pat. No. 5,569,016 to Mokler; U.S. Pat. No. 6,065,925 to Carson, et al; U.S. Pat. No. 5,807,065 to Kuhl; and U.S. Pat. No. 6,106,219 to Newsome et al. These patents represent attempts to provide automated systems for efficiently moving stacks of articles from one location to another or removing the articles form the stacks one piece at a time.
However, a specialized need exists for a stacking and conveying device for use in the postal system, which the devices described in the above-referenced patents do not address. In the postal system, an extraordinarily large amount of mail passes through centralized postal centers, which must be sorted and then transported on to local post offices for distribution. In these postal centers, specially sized cartons or containers with lids are used to place pieces of mail destined for the same postal areas together or to otherwise contain numerous and various articles for transport without loss or misplacement of any articles. Generally, large, box-shaped plastic or cardboard containers or trays are used with specially formed lids which are cut and sized to fit into the tops of the containers. The lids typically have notched corners and creases at their edges to facilitate folding of the notched portions and edges upon application of the lids into the open tops of the containers.
Conveyor systems are typically employed to move the cartons or containers along for manual or automatic filling with articles of mail. However, the specially formed lids must be manually folded and applied to the containers, specifically, inserted to fit tightly into the tops of the containers. This is obviously a time consuming process and often requires pausing the conveyor system which handles the postal trays or cartons full of mail so that the individual applying the lids to the tray can keep up, or catch up, with the automatic conveyor system. The person applying the lids must also retrieve and stack enough lids to apply to the stream of cartons, and periodically stop the conveyor system to resupply the stack of lids once it has been depleted.
Thus, a need exists for an automatic assembly for stacking, aligning, conveying and applying lids onto containers so that the containers can more quickly and efficiently be covered and transported off to their respective destinations, without the need to periodically pause the conveyor as it conveys the lids.
Therefore, a general object of the present invention is to provide an assembly for stacking, aligning, conveying and lifting numerous lids for containers to allow automatic application of the lids onto containers.
It is a further object of the present invention to provide a conveyor system which can move a plurality of stacks of the lids from an input end to an output end.
It is another object of the present invention to provide a stacking and feeding area or column at the input end of the conveyor which is manually loaded and which aligns a stack of lids before transporting the stack on the conveyor.
It is yet another object of the present invention to provide a plurality of vertical guide rods at the stacking and feeding area of the conveyor for proper alignment of the lids.
A still further object of the present invention is to provide a first pair of is pivotable guide rods at the stacking and feeding area of the conveyor which move out of the path of the lid stack when the stack is full and moved from the stacking and alignment column.
Another object of the present invention is to provide a two-strand conveyor belt which allows the conveyor system to be accessed from below to allow the vertical feed assembly to advance between the belts, and which has a length that will allow numerous stacks of aligned lids to be conveyed thereon.
Yet another object of the present invention is to provide a second set of pivotable guide rods at an output end of the conveyor which pivot out of the path of the conveyed stacks to allow the stack to enter into a vertical feed area.
Still another object of the present invention is to provide a vertical feed area at the output end of the conveyor which lifts a stack of lids vertically from the conveyor surface to allow the topmost lid on the stack to be removed and transported for application onto a container.
A further object of the present invention is to allow the conveyor to continue indexing stacks forward from the input end to the output end while the vertical feed assembly is engaged.
Another object of the present invention is to allow the assembly to be used in combination with means for lifting the topmost lid on a stack and transferring it to a second conveying area and means for automatically applying the lid to the top of a container.
In order to meet these and other objects, the present invention generally comprises a preferably double-belt conveyor, a stacking and alignment region for a magazine of generally flat articles at one end of the conveyor defined by a first set of guide rods, and a vertical feeding region at an opposite end of the conveyor defined by a second set of guide rods, each of the first and second set of guide rods including a pair of pivotable rods. The assembly preferably includes means for lifting and transporting the topmost lid from a stack of lids in the vertical feeding region to a second conveyor area and means for applying the lid to a container.
The conveyor has oppositely disposed input and output ends. At the input end of the conveyor, four inboard guide rods are positioned to define a stacking and alignment region or column for a vertical stack of articles, in this case, container lids. Two of the four guide rods are fixed, or unmoveable, while the other two guide rods are pivotable, such that after a stack of lids is lowered into the stacking and alignment region, the two pivotable guide rods are pivotable out of the path of the stack of lids as it moves from the stacking and alignment column 14 for transport to the output end. The four guide rods are spaced to fit into respective notched corners of the container lids and served to align the stack of lids as they are manually loaded into the stacking region or column.
After the stack of lids is full, the pair of pivotable inboard rods on the conveyor pivot out of the path of the stack as it is conveyed out of the stacking and alignment column 14. The conveyor indexes forward to allow another stack to be loaded into the stacking and alignment column. A series of stacks are thus loaded, aligned, and moved out of the stacking and alignment column 14 in the same manner, until the conveyor surface is full of adjacently arranged stacks of lids.
The stacks of lids are conveyed toward the out put end of the conveyor, where the vertical feed column, defined by four guide rods, including a pair fixed guide rods and a pair of pivoting guide rods, is located. As the foremost or lead stack on the conveyor surface approaches the vertical feed region, a second pair of pivoting guide rods swings open out of the path of the lead stack to allow the stack to enter the vertical feed region. The lids are conveyed up against the fixed rods at the far-most end of the conveyor to square the stack. The feed conveyor stops, and the second pair of pivoting guide rods swing close to assist in squaring and guiding the stack.
After the stack is squared and aligned properly in the vertical feed region, a vertical lid feeder, which preferably comprises a plate mounted or attached to a linear actuator, is advanced until an upper limit is reached. After each subsequent upward advancement of the vertical feeder, the uppermost lid in the stack is removed, such as by a vacuum or suction device, and transported to a second, container conveying area where it is applied onto the top of a container. This upper limit is preferably determined by a sensor. Once the upper limit is reached, the feeder stops and remains at rest until a number of lids have been removed. The sensor also works to detect a lower limit of the vertical feeder, such that when this lower limit is sensed, the vertical lid feeder advances until the upper limit is sensed, and the above-described process is repeated.
When a complete stack of lids has been removed from the vertical feed region, a vertically mounted sensor detects that the stack is empty. The lid feeder then fully retracts, the inboard rods pivot open, and the next stack moves into the vertical feed region.
An important feature of the present invention is the ability of the conveyor to continue to index the stacks of lids along the conveyor surface while the vertical feed assembly is engaged. That is, each stack of lids continues to be moved forward from station to station as it is conveyed from the input end to the output end until the stack reaches the second set of pivotable guide. This allows the operator of the assembly to continue to load the stacking and alignment column and index several stacks forward while the vertical feed assembly continues to operate, without having to pause the conveyor and have unwanted xe2x80x9cdowntimexe2x80x9d.
The above-described conveyor system is especially contemplated for use with a lid transport and application apparatus and a second, container conveyor system. In this application, the lid transport and application apparatus picks up the topmost lid in the stack contained in the vertical feed region, preferably by vacuum or suction means, and transport the lid horizontally from the lid conveyor assembly to a second conveyor assembly, upon which a series of tubs or containers are moved. The lid transport and application apparatus moves the lid to a location above a container to be covered, then lowers the lid onto the top of the container while simultaneously folding the edge flaps of the lid downward for insertion into the container. The second conveyor then indexes the covered container forward and moves the next container to be covered into position.
The present invention also contemplates a method for stacking, aligning, conveying, and vertically feeding a plurality of stacks using the above-described apparatus.